CiteULike: suizans Miller

Perceptual space for musical structures

James Miller — 2007-01-02T13:15:31-00:00

The Journal of the Acoustical Society of America, Vol. 58, No. 3. (1975), pp. 711-720.

Individual subjects with or without musical training made similarity judgments of pairs of tones on a nine-point scale. Each subject was run in three or four sessions of 351 trials each. The tones had structures like those of musical instruments, being made of all 27 combinations of three dimensions, each at three levels. In Experiment 1, the dimensions were fundamental frequency F0, envelope, and relative amplitudes of harmonics. In Experiment 2, the dimensions were number of harmonics, envelope, and onset rate of harmonics. Analysis of data by means of multidimensional scaling showed a strong context effect. In Experiment 1, F0 had such high saliency that for most subjects no other dimension was present in perceptual space and thus no differences were found between musical and nonmusical subjects. By holding F0 constant in Experiment 2, subjects were able to use harmonic as well as envelope structure in judgments. Differences between musical and nonmusical subjects appeared, and we discuss the basis for these differences. For both experiments, the curve relating latency of response to similarity was parabolic and, although a given subject's perceptual space changes little over successive runs, there is some evidence from Experiment 2 that musical subjects have the more stable space of perceptual dimensions.Subject Classification: 65.52, 65.75; 75.10. doi:10.1121/1.380719 PACS: 43.65.+v, 43.75.+a Additional Information Full Text: [ PDF (874 kB) GZipped PS

NEUROSCIENCE: Spying On New Neurons in the Human Brain

Greg Miller — 2007-11-09T18:42:10-00:00

Science, Vol. 318, No. 5852. (9 November 2007), pp. 899a-900.

10.1126/science.318.5852.899a

An Increase in Lactate Output by Brain Tissue Serves to Meet the Energy Needs of Glutamate-Activated Neurons

Avital Schurr — 2006-11-09T22:07:09-00:00

J. Neurosci., Vol. 19, No. 1. (1 January 1999), pp. 34-39.

Aerobic energy metabolism uses glucose and oxygen to produce all the energy needs of the brain. Several studies published over the last 13 years challenged the assumption that the activated brain increases its oxidative glucose metabolism to meet the increased energy demands. Neuronal function in rat hippocampal slices supplied with 4 mM glucose could tolerate a 15 min activation by a 5 mM concentration of the excitatory neurotransmitter glutamate (Glu), whereas slices supplied with 10 mM glucose could tolerate a 15 min activation by 20 mM Glu. However, in slices in which neuronal lactate use was inhibited by the lactate transporter inhibitor a-cyano-4-hydroxycinnamate (4-CIN), activation by Glu elicited a permanent loss of neuronal function, with a twofold to threefold increase in tissue lactate content. Inhibition of glycolysis with the glucose analog 2-deoxy-D-glucose (2DG) during the period of exposure to Glu diminished normal neuronal function in the majority of slices and significantly reduced the number of slices that exhibited neuronal function after activation. However, when lactate was added with 2DG, the majority of the slices were neuronally functional after activation by Glu. NMDA, a nontransportable Glu analog by the glial glutamate transporter, could not induce a significant increase in slice lactate level when administered in the presence of 4-CIN. It is suggested that the heightened energy demands of activated neurons are met through increased glial glycolytic flux. The lactate thus formed is a crucial aerobic energy substrate that enables neurons to endure activation.

Interhemispheric switching mediates perceptual rivalry

Steven Miller — 2007-11-01T21:29:08-00:00

Current Biology, Vol. 10, No. 7. (1 April 2000), pp. 383-392.

Background: Binocular rivalry refers to the alternating perceptual states that occur when the images seen by the two eyes are too different to be fused into a single percept. Logothetis and colleagues have challenged suggestions that this phenomenon occurs early in the visual pathway. They have shown that, in alert monkeys, neurons in the primary visual cortex continue to respond to their preferred stimulus despite the monkey reporting its absence. Moreover, they found that neural activity higher in the visual pathway is highly correlated with the monkey's reported percept. These and other findings suggest that the neural substrate of binocular rivalry must involve high levels, perhaps the same levels involved in reversible figure alternations. Results: We present evidence that activation or disruption of a single hemisphere in human subjects affects the perceptual alternations of binocular rivalry. Unilateral caloric vestibular stimulation changed the ratio of time spent in each competing perceptual state. Transcranial magnetic stimulation applied to one hemisphere disrupted normal perceptual alternations when the stimulation was timed to occur at one phase of the perceptual switch, but not at the other. Furthermore, activation of a single hemisphere by caloric stimulation affected the perceptual alternations of a reversible figure, the Necker cube. Conclusions: Our findings suggest that interhemispheric switching mediates perceptual rivalry. Thus, competition for awareness in both binocular rivalry and reversible figures occurs between, rather than within, each hemisphere. This interhemispheric switch hypothesis has implications for understanding the neural mechanisms of conscious experience and also has clinical relevance as the rate of both types of perceptual rivalry is slow in bipolar disorder (manic depression).

Inferring the Popularity of an Opinion From Its Familiarity: A Repetitive Voice Can Sound Like a Chorus

Kimberlee Weaver — 2007-06-11T08:48:14-00:00

Journal of Personality and Social Psychology, Vol. 92, No. 5. (May 2007), pp. 821-833.

Despite the importance of doing so, people do not always correctly estimate the distribution of opinions within their group. One important mechanism underlying such misjudgments is people's tendency to infer that a familiar opinion is a prevalent one, even when its familiarity derives solely from the repeated expression of 1 group member. Six experiments demonstrate this effect and show that it holds even when perceivers are consciously aware that the opinions come from 1 speaker. The results also indicate that the effect is due to opinion accessibility rather than a conscious inference about the meaning of opinion repetition in a group. Implications for social consensus estimation and social influence are discussed.

Mapping research journeys across complex terrain with heavy baggage

Nod Miller — 2005-02-05T23:03:27-00:00

Studies in Continuing Education, Vol. 26, No. 3. (2004), 405.

The evolutionary genetics of personality

Lars Penke — 2007-09-01T18:31:10-00:00

European Journal of Personality, Vol. 21, No. 5. (2007), pp. 549-587.

Genetic influences on personality differences are ubiquitous, but their nature is not well understood. A theoretical framework might help, and can be provided by evolutionary genetics. We assess three evolutionary genetic mechanisms that could explain genetic variance in personality differences: selective neutrality, mutation-selection balance, and balancing selection. Based on evolutionary genetic theory and empirical results from behaviour genetics and personality psychology, we conclude that selective neutrality is largely irrelevant, that mutation-selection balance seems best at explaining genetic variance in intelligence, and that balancing selection by environmental heterogeneity seems best at explaining genetic variance in personality traits. We propose a general model of heritable personality differences that conceptualises intelligence as fitness components and personality traits as individual reaction norms of genotypes across environments, with different fitness consequences in different environmental niches. We also discuss the place of mental health in the model. This evolutionary genetic framework highlights the role of gene-environment interactions in the study of personality, yields new insight into the person-situation-debate and the structure of personality, and has practical implications for both quantitative and molecular genetic studies of personality. Copyright © 2007 John Wiley & Sons, Ltd.

The left hemisphere's role in hypothesis formation.

G Wolford — 2005-08-31T19:18:14-00:00

J Neurosci, Vol. 20, No. 6. (15 March 2000)

In a probability guessing experiment, subjects try to guess which of two events will occur next. Humans tend to match the frequency of previous occurrences in their guesses. Animals other than humans tend to maximize or always choose the option that has occurred the most frequently in the past. Investigators have argued that frequency matching results from the attempt of humans to find patterns in sequences of events even when told the sequences are random. There is independent evidence that the left hemisphere of humans houses a cognitive mechanism that tries to make sense of past occurrences. We performed a probability guessing experiment with two split-brain patients and found that they approximated frequency matching in their left hemispheres and approached maximizing in their right hemispheres. We obtained a conceptual replication of that finding on patients with unilateral damage to either the left or right hemisphere. We conclude that the neural processes responsible for searching for patterns in events are housed in the left hemisphere.

The Family Check-Up: A Pilot Study of a Brief Intervention to Improve Family Functioning in Adults

Lisa Uebelacker — 2006-05-11T00:22:29-00:00

Family Process, Vol. 45, No. 2. (June 2006), pp. 223-236.